Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations, so the description carries the burden and largely does: it discloses the 200-transaction/year limit, the upgrade-to-Pro/Business consequence of exceeding the cap, that AI credit counts are unpublished, and that bank-feed/cash receipts are excluded from the gate. It stops short of stating explicitly that this is a pure side-effect-free read, though 'Return' implies it.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The scoping and mode logic is front-loaded and efficient, but the description embeds the full eight-country threshold table in parentheses — data the tool itself returns — which bloats a spec that should be lean. That parenthetical is redundant payload an agent doesn't need in order to decide to call.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description adequately characterizes the three return shapes (full table, single threshold, `freeEligible` verdict with headroom math). Exact response fields aren't spelled out, but enough is given for correct invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and already documents the enum, the home-currency-not-USD rule, and the bank-feed exclusion. The description largely restates those same points rather than adding new meaning, so baseline 3 is warranted.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource — 'Return the HelloBooks Free-plan annual-invoice-turnover thresholds' — and scopes it to the 8 priced markets. No sibling tool deals with pricing thresholds, so an agent can route here unambiguously.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly maps each input mode to an outcome: 'Call with no args to get the full table, with `country` for one threshold, or with `country` AND `annualInvoiceRevenue` ... for a `freeEligible` verdict.' Clear operational guidance, though no sibling alternative or when-not-to-use case is named.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.